Treating ferrous sheets and plates



Patented Oct. 31, 1933 UNITED STA PATENT orF cE poration of New Jersey No Drawing. Serial No Application September28, 1931 Claims. (01. 148-4) This 'invention'relates to the manufacture of rolled sheets and plates such as tin'plate and similar ferrous metal materials which, after beingrolled, are pickled and then washed, and after 5 being formed into a pile are later subjected to abox annealing operation preparatory to further finishing operations. 7

A most tedious and troublesome operation in the manufacture of such materials, and particularly tin plaw, has been the separation of the hot rolled sheets or plates in an annealed pile after the first box annealing operation. This separation, known as opening, is essential because the pile of' sheets or plates have become welded together or adherent in varying degrees while undergoing the heat treatment to which the piles are subjected in such annealing operations. The same difliculties are encountered but to alesser extent in box annealing the cold rolled materials.

After the annealing operation it is necessary for each sheet to befreed from any temporary union with the others of the pile so as to be ready for subsequent processing or use. While all of the sheets or plates in an annealing charge are not usually stuck together in the manner indicated, such condition is present to a very con-' siderable extent in practically every annealed pile of hot rolled material and to a degree in annealed piles of cold rolled materials. The result is that the slow, laborious and costly process of manually opening a pile of annealed materials has'heretofore been a regular and unescapable feature of the mill routine.

The primary object of this invention 'is the provision of improved means whereby the objectionable welding or sticking together of the sheets and plates ordinarily present after the box annealing operation is prevented or, to a large extent, overcome, and the labor necessary in opening the materials inreadiness for cold rolling and further treatment is reduced to a minimum; likewise, a substantial elimination of the destructive staining of the surfaces of the sheets,

5' or plates generally present in the methods used heretofore is effected in a simple, rapid andeconomical manner. 7 A

Still further objects of the invention will be made apparent hereinafter in a detailed description and the appended claims.

In the practice of the improved method the sheets or plates, after the removal of the scale and prior to annealing, are treated by dipping them in a suitable aqueous mixture or chemical solution, preferably a solution of a zinc compound 7 would act effectively and at the same time would such as solutions of zinc chlorid zinc sulfate or -zinc oxid.

With existing tin mill equipment it is possible to provide for the zinc compound treatment by adding the chemical in proper proportions to the rinse or wash tank at the pickler. A concentra-' tion of approximately 0.05 per cent. zinc chlorid, zinc sulfate or zinc oxid in the wash water has been found sufficient to accomplish the desired results. Thus,'the sheets or'plates, as soon as the oxid or scale has been removed by the action of the pickling operation, are. immersed, rinsed and treated in a dilute'solution of zinc chlorid, zinc sulfate or zinc oxid after which they are inspected in the usual manner and arranged in piles for the black annealing operation. I

A'more economical and effective method is to provide an additional dipping tank in which the sheets or plates to be treated are immersed in the solution or aqueous mixture. after having been rinsed with water in the wash tank.

Whatever portion of the solution or mixture adheres to the sheets or plates as they are formed into piles on the charging stands is allowed to. remain on the surfaces. I

It has been found that this treatment practically eliminates troublesome sticking or welding of thesheets or plates in the subsequent annealing process; that better annealing is obtained; that the annealing temperature can be raised at least 100 degrees Fahrenheit; that the opening operation is greatly facilitated and that the spoilage of many sheets or plates in the opening operation is avoided. A reduction of approximately 50 percent. in the cost of opening is thus effected.

Another apparent advantage of this treatment is a material reduction in the amount of destructive staining on the surfaces of the materials which heretofore has contributed to the production of defective coatings.

While the fundamental concept of this invention lies in the use of a separating medium between sheets in a box annealing operation one important feature was to find materials that not, by their presence, interfere with subsequent operations. In designating a concentration of 0.05 per cent. of zinc compound as satisfactory I have given this figure only as being representative of the approximate minimum desirable in one particular embodiment of the invention.

Higher and lower concentrations may be maintained and the manner of application of the solution may be modified so that it will fit into any procedure for the production of ferrous metal plates and the like. Concentrations as low as 0.001 per cent. and as high as 0.20 per cent. have been found to give beneficial and satisfactory results.

The advantages of my invention will be apparent to those skilled in the art. The materials used in forming the aqueous mixture with which the sheets and plates are treated are not limited to those specifically mentioned herein and other changes may be made Within the scope of the invention, as defined by the claims.

I claim:

1. The method of preventing sticking in box annealing sheets and plates which consists in chemically. treating the rolled and pickled sheets or plates by immersion in an aqueous solution of zinc sulfate of a concentration of 0.001 to 0.20 per cent, piling the treated materials and then box annealing the piles.

2. The method of preventing sticking in box annealing sheets and plates which consists in chemically treating the rolled sheets and plates in an aqueous solution of zinc sulfate of a concentration of,approximately .05 percent., piling the treated materials and then box annealing the piles.

3. The method of preventing sticking in annealing sheets and plates which consists in chemically treating the rolled and pickled sheets and plates by immersion in an aqueous solution of a zinc compound from the class consisting of zinc chlorid, zinc sulfate and zinc oxid, prior to annealing the materials and then annealing piles of the materials so treated.

4. The method of preventing sticking in annealing sheets and plates which consists in chemically treating the rolled and pickled sheets and plates by immersion in an aqueous solution of a zinc compound, from the class consisting of a zinc chlorid, zinc sulfate and zinc oxid of a concentration of approximately .05 per cent. prior to annealing, piling the treated materials and then annealing the piles.

5. The method of preventing sticking in annealing sheets and plates which consists in chemically treating the rolled and pickled sheets and plates by immersion in an aqueous solution of a zinc compound, from the class consisting of zinc chlorid, zinc sulfate and zinc oxid of a concentration of .001 to .2 per cent., piling the treated materials andthen annealing the piles.

- RUFUS E. ZIMMERMAN. 

